铜镉复合胁迫下硫素对小麦幼苗铜镉吸收、亚细胞分布及毒性的影响

摘要

采用水培的方法,研究了不同硫素供应水平对铜镉复合胁迫(Cu+Cd:10μmol·L-1+10μmol·L-1)下,小麦幼苗铜镉吸收、亚细胞分布及生理毒性的影响.结果表明,缺硫和高硫处理均降低了小麦幼苗根系和叶片中铜和镉的含量,不同硫水平处理对小麦幼苗根系亚细胞各组分中镉的分配比例没有产生影响,而对铜亚细胞组分的分配比例则产生了显著影响,表现为添加硫的处理细胞质组分分配比例增加,细胞壁组分的分配比例降低,缺硫处理则相反.铜镉复合胁迫对小麦幼苗产生明显的毒性作用,使其生长受到抑制、叶绿素含量降低、小麦幼苗MDA含量增加、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性降低以及还原性谷胱甘肽(GSH)含量降低.与适中硫处理相比,高硫处理能明显缓解铜镉复合胁迫对小麦的毒害,可以促进小麦幼苗生长,增加幼苗中叶绿素含量,提高SOD和CAT的活性,降低MDA在根系中的积累,提高根系GSH的含量,而缺硫处理则相反.%A solution culture experiment was carried out to investigate the effects of sulfur on the uptake, subcellular distributions and toxicity of copper (Cu) and cadmium (Cd) to wheat seedlings. The result indicates that both the high sulfur and no sulfur treatment could decrease Cu and Cd content in the roots and leaves of wheat seedlings. Different sulfur supply levels did not affect the subcellular distributions of Cd in the roots of wheat seedlings, while it induced significant changes on the subcellular distribution of Cu. The treatment supplied with sulfur increased the allocation proportion of Cu in soluble fraction and decreased it in cell wall fraction, while opposite results were concluded in no sulfur treatment experiments. Combined treatment of Cu and Cd generated obvious toxicity to wheat seedlings. Specifically, they made decrease in plant biomass, chlorophyll content, reduced glutathione (GSH) content and the activities of superoxide dismutase (SOD) and catalyses (CAT), and increase in the content of MDA in wheat seedlings roots. Compared with moderate sulfur treatment, high sulfur treatment significantly increased the plant growth, the content of chlorophyll and reduced glutathione (GSH), and the activity of superoxide dismutase (SOD) and catalyses (CAT), whereas clearly decreased the content of M DA in wheat seedlings. The non - sulfur treatment results were adverse.